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Featured Stone:

 

Fancy Color Tanzanite

 

Refractive Index:  1.69 - 1.67 Crystal Structure: Orthorhombic 
 

 

 
Hardness:  6.5 Specific Gravity:  3.35
 

 

 
Chemical Composition: Ca2Al3Si3O12(OH) Occurrences:   Tanzania

The standard blue violet color of Tanzanite has become a classic in the gem world.  It is a color, however, that depends almost entirely on heat-treating natural color rough.  More correctly called Zoisite (the more marketable name Tanzanite came shortly after its discovery), the natural color range is typically a dark brown to greenish brown, quite removed from the vibrant and attractive material we know as Tanzanite.

There are however a small percentage of natural stones that are recovered in other colors.  These are known variously as Fancy Tanzanite, Mardi Gras Tanzanite or simply {insert color here, i.e. green, yellow, etc.} Tanzanite.  Only recently have these stones began to be appreciated for the unique material that they are, as opposed to being heated with the standard color material.  And the range is fairly wide, from deep sapphire blue to rich yellows and, as we shall see, even some pinks.

Interest in these fancy colors began to intensify after the discovery of some very attractive and vibrant grass green stones over a decade ago.  This was a unique find of almost Tsavorite colored material that produced some spectacular stones and has set the standard for green, sometimes called 'chrome', Tanzanite ever since.  This attractive green seems to be second only in rarity to true pink stones.  Pink Tanzanite is extremely unusual and many dealers have not seen or heard of this material.  Because of Tanzanite's strong pleochroism, small light colored heated Tanzanites can appear pink in certain directions and lighting conditions, but despite the confusion, undisputed pink stones do in fact exist.

With rising interest comes rising prices and since the virtual disappearance of Tanzanite rough from the marketplace, expect prices to continue upward on all colors of Tanzanite.  The Tanzanian government has assumed much greater control over the Tanzanite market in the last two years and it is likely that fancy Tanzanite will become even more difficult to obtain, as a greater number of stones are subjected to heating in order to obtain the classic Tanzanite color.  This, coupled with the continued interest in these unusual stones, is likely to exert more upward pressure on prices.